Electron discharge tube



Feb. 6, 1934.

H. w. PARKER 1,945,979.

ELECTRON DISCHARGE TUBE Filed May 21, 1932 Patented Feb. 6. i934 UNETEDSTAT-ES sc atic PAT signor to Rogers Toronto, Ontario, Canada, acorporation Ontario, Canada Radio .Tubes, 0

Application May 21, 1932. seen No. 612,763 3 Claims. '(ci. 25o-2'z.5)'

I My invention relates to electron discharge tubes andpertainsparticularly to that type of such tubes which are termed thermionictubes.

One of the objects contemplated by my invention consists in providing athermionic tube of' extreme simplicity.

Another object contemplated ing no lead-in wires for making contact withthe electrodes thereof.

An additional object contemplated by my in vention comprises producing athermionic electron discharge device of such nature that the same may beconstructed in small dimensions.

A further object contemplated by my'invention consists in providing anelectron discharge device employing no internal electrodes for thepurpose of producing a luminous spot of fluorescent light.

A still iurther object contemplated by my invention comprises producinga thermionic tube in which the walls of the tube are partiallyconstructed of the electrodes therefor.

I accomplish all of the above noted desirable results and others whichwill hereinafter be pointed out and discussed by a novel design ofelectron discharge device in which the evacuated envelope within whichthe electron discharge takes place is composed of alternate metallicsections and vitreous sections, the metallic sections of whichconstitute the electrodes of th tube.

In the drawing accompanying and forming a part of this specification andin which like reference numerals designate corresponding partsthroughout: g

Fig. 1 illustrates a substantially full size elevation of my novel tube.

I Fig. 2 is an end view of the same. t Il' ig. 3 is an enlarged sectionof my improved u e. i

Fig. 4 illustrates my improved tube in position in a contacting sockettherefor.

Fig. 5 is a sectional view of one form of cathode heater.

Fig. 6 is an end view of my time in position in its contacting socket,showing the method of making contact with the eatho'de heater element.

Referring now particularly to the Figs. 1, 2, and '3, which illustrate apreferred form of one type of construction of my improved'tube, the tubecomprises substantially tubular metallic sections 1, 3, and 5, which areunited by vitreous sections as 2 and 4. -The metallic sections arewelded to the glass or vitreous tube sections by my invention; consistsin providing a thermionic tube requirin any well known manner and thereis provided in the type of, tube illustrated a vitreous transparent cap6 coated on the inside with any suitable material 7 which becomesfluorescent upon bombardment by electrons, such asv zinc sulphide. 0

The metallic section 1 is in the form of a cap and bears on' thein'sidethereof a coating 9- of electronemissive substance such as barium oxide,or bther substance capable of emitting electrons at'relativeh lowtemperatures. I

There is further provided'dn the -'vitreous secv tion 4 ari exhausttubulation 8 through which. the tube may be exhausted and thereaftersealed.

The embodiment of my tube illustrated isintended for use with televisionreception systems 79 in which small individual light areas may bemodified in luminous intensity corresponding to the picture detail. Itherefore, in this embodiment of my device, prefer to construct'the tubeof relatively small diameter, and for that'pur- 75. pose employ for themetallic sections of the tube such metals as molybdenum, nickel orcopper and for the vitreous sections of thetube either lead glass or lowexpansion borate glass. 7,

Obviously, the electron emissive substance-9 o may be rendered active bythe application of heat in any convenient manner. A preferred way ofaccomplishing the desired result is shown in Figs. 4, 5, and 6. Theheater comprises a cap 10 of refractory insulating material throughwhich 35 is threaded a high resistance heating wire 12, the extremitiesof which are welded to standards to form contact terminals 13 and 14 andthe heater cap is provided with a disc 11- of heat resistant insulatingmaterial such as mica. i The cap 10, when placed over the end of themetallic section 1, is held in place by means of terminal spring clips20 and 21, which bear against the terminals oi. the heater 13 and 14 andmake contact therewith. The tube may be supported in a series of. springclip terminals 15, 16, l'land 18. secured to a base. 19 of insulatingmaterial. a

The metal section 3 serves as the control grid of the tube while themetal section 5 serves as the anode. When the tube is'used for thepurpose of producing a spot 0! variable illumination due to the actionof the electrons upon the fluorescent material 7, the section 3functions as a control or focusing cylinder to control the intensity ofthe bombardment of the fluorescent material and hence its luminosity inaccordance with the garying potentials applied to the control cyliner 3.I

Contact with the cathode section-s1 may be made thrdugh either springclip 15 or 16, while It will be obvious from the foregoing that myimproved tubecan be made in extremely small dimensions and that theembodiment of my tube described herein may be made in sufilciently smalldimensions to be used as an individual variable light area fortelevision reception systems or that, further, the tube may be used as avisual indicator of electrical intensities varying at comparatively highfrequency. The simplicity of my thermionic tube is obvious from the factthat as all of the electrodes of the tube form of the wall of the tube,there is no necessity for lead-in wires.

My experiments have indicated thatthe heat required for the cathode isextremely'smali and that eificient electron emission can he achievedfrom the material 9 by a degree of heat which does not cause the metalsection 1 to become visibly red.

Obviously, if the tube is intended for use as a detector, relay oramplifier, the vitreous cap 6 may be dispensed with and the end of theanode section 5 closed to form a metallic cap.

While I have illustrated and described one preferred embodiment of onetype of my improved tube, it is to be understood that I may vary thedetails thereof Without departing from the spirit or narrowing the scopeof my invention? Having thus completely described my invention what Iclaim as new and desire to secure by Letters Patent of the United Statesis as follows: 7

1. A thermionic tube comprising, a substan tially evacuated container,having walls comprising alternate metallic and vitreous tubular sectionsand end portions, one of said end portions comprising a metallic cupbearing an electron emissive substance on the interior thereof andadapted to function as a cathode through the direct application of heatto the exterior thereof, the other end portion comprising a cap coatedon the interior thereof with a material adapted to be renderedfluorescent through bombardment by electrons and the metallic sectionsof said tube comprising respectively the grid and anode of said tube.

2. An electron discharge device comprising a partially evacuatedcontainer, having walls comprising alternate vitreous and metallictubular sections and end portions, one-of said end portions comprising ametallic cup bearing an electron emissive substance onthe interiorthereof and adapted to function as a cathode through the directapplication of heat to the exterior thereof, the other end portioncomprising a vitreous cap coated on the interior thereof with asubstance adapted to be rendered fluorescent through bombardment byelectrons and the remaining metallic sections constituting the onlyremaining electrodes of said tube.

3. An electron discharge device comprising, a partially evacuatedcontainer, having walls comprising alternate vitreous and metallictubular sections and end portions, one of said end por- 'tionscomprising a metallic cup coated on the inner end surface only with anelectron emissive substance and adapted to function as a cathode throughthe direct application of heat to the exterior thereof, the other endportion comprising a transparent vitreous cap coated onthe in-

